This is Scientific American 60 Second Science.

I'm Christine Herman.

Anyone who's ever been with a toddler can tell you.

If they're upset about something, they will let you know.

Scientists have been aware of this behavior,

but what they did not know until now

is that if babies as young as a year and a half old

see someone else being treated unfairly,

they expect the leader, the parent,

or the caregiver in that situation to step in and do something

about it.

Babies evaluate others constantly.

Renee Byardjon is a psychologist at the University of Illinois.

She led the research on babies expecting fairness.

When these transgressions occur, babies evaluate parents and other leaders and say, well, you saw this transgression, you know this is not fair,

are you going to do something about it?

If you don't, then you are shirking your responsibilities and it makes you

less of a leader, less of a parent.

That's right, babies are judging you.

Byer Jean says it seems babies are born with these expectations of what a

leader is and how they should behave. The work is in the proceedings of the National Academy

of Sciences. The researchers used bear puppets to perform skits for 17-month-old babies

...